Moving stairway



June 13, 1935- w. s. GRAFF-BAKER MOVING STAIRWAY Filed July 6, 1934 7 Sheets-Sheet l ATTORNEY Illlllllflll'lllllllll June 18, 1935 W. S. GRAFF-BAKER MOVING STAIRWAY Filed July 6, 1934 7 Sheets-Sheet 2 ATTOR NLY BY Marlin:

n 18, 1935. WQ 5. GRAFF-BAKER "2,005,061

MOVING STAIRWAY Filed July 6, 1934 7 Sheets-Sheet 3 WM 1mm Mfl-Qiwlag INYENTOR AT TOR NEY June 18, 1935. w. s. GRAFF-BAKER movmc STAIRWAY Filed July 6, 1934 7 Sheets-Sheet '4 Y WM 8% 84* INVENTOMRY BY ATTORNEY June "18, 1935. I w. $.GRAFF-BAKER MOVING sTAIRwAY Filed July 6, 1954 7 Sheets-Sheet 5 WM 8.1mm; ax fvwmven-ron BY ATTORNEY j Juri 18, 1935- w. s. GRAFF-BAKER 2,005,067

' MOVING STAIRWAY Filed July 6, 1934 v 7 Sheets-Sheet 6 I Fl-0.20 L

Why-am "ufi-BMINVENTOR BY i'flllii ATTORNEY June 18, 1935. w, s, GRAFF-BAKER 2,005,067 0 22 FIQZI 1 41 I 191 13,9

I MA Sm duf Hi h INVENTOR BY 1" ATTORNEY Patented'JunefIB, j j I STAT-ES T:p-OFFICE] .7 M VI NGj'STAmWAY I mi nems-Baker, memes Lon-f don, England, assignor to Otis ElevatorCom-- pany', .Ne'w York, N. Y., a corporation of New 4 Jersey Application July fi, :1 934, Seria l.No. 733,975 I 1 i Inv GreatBritain July 10, 1933 1 e 9 Claims. (c1. 1 9816) This invention relates to'moving Stairways. step tread, and secured to the underside'thereoi, It is the object of this invention touprovidea assuming the stepunit to been the working run; moving stairway which is of simple design, which of the stairway, Only one tread wheel track, at is compact, especially at the landings, and which the center of the stairway, isthereforerequired., is silent and safe i'noperation-g 1 While the step units are on-v the inclinepor- 5 Among the features of the moving stairway vin tion of the working run of the stairway-at which accordance .with this invention are thefollowing: time the step unitsqare instairformation ;with The stairwayisformed of an endless seriesfof each step tread in an inwardly rotatedposition' step units each hinged or pivotally connected-to with respect to its corresponding step pocket;-.-

10 the next adjacent step'unit. The primary elethe free end of each step tread-is supported by its 10 ments of each step unit are-the stepspocketor corresponding step pocket. .While thesteplunits' frame and the step tread. Each step "pocket is are on the return run of the stairway-+atwhich formed with three sides, two ofv which', --one' at time the step units are inverted and each step 1 1 each side of the stairway, are parallel to the tread is in an outwardly-rotated position with re-- 5 longitudinal axis of -the"stairwayand arettermed spect to its corresponding-steppocket-+the ,free "longitudinal sidest Thef' third side a-extends end ofeach step tread is likewise supported by itse transversely across "the stairway to connect the corresponding "step pocket. *"Theztre'ad wheel. two long-itudinalsides, and is termedthe transtrack for the-tread wheel's thus'needsto be pro ,vers'e side. Adjacent step pockets tare pivotally vided only in the vicinity 10f 'thexlandings, and.

connected, preferably'ateachside of the stairmay be dispensed with'elsewhere. H Thesupportyzo way, with a rod extending transversely across the for the free end of the steptread when in its in-.

stairway connectingcorresp'o'nding' hinge or pivot wardly rotated position conveniently comprises points at opposite sides of thestairway. These two projections or stops vat either-side of the rods are termed step axles. A step wheel is stairway'extending' from the'transverse side of rotatably mounted on each step axleat each'side the step pocket near the bott'om edge thereof into of the stairway,'and tracks for these step wheels the path of the step tread so as to engage the are provided to support and guide thestep unit s underside of the step tread."These projections throughout the working and return runs 'of the 01' stops likewise serve to define 'the limit-'ofthe'l stairway. Each step tread is pivotally supported inward motion of the step tread." The support adjacent its nose to its corresponding step pocket, for the free end of the step tread when in its'out-' 30 preferably by pivotallymounting the step tread wardly rotated position conveniently comprises upon the step axle for such step pocket.- Each an extension of the step'tread bracketupon which step tread may thus rotate relatively to the sides the tread wheel is mounted, such extension being of its associated step pocket, the transverse side shaped so that it engages the'bottom'edge; of f.

thereof being curved so that there is a small, unithe transverse side of the step-pocket. Such ex- 35 form clearance between it and the free end ofthe tension, in conjunction with the transverse'side, step tread as the step treadmoves relative therealso serves to definethelimit of the-outward mo to. The transverse side of the step pocket of one tion of the step tread; 11 step unit thus serves as "the'riser. for the step The endless stairway running gear chain'may' 4o tread of the next adjacent'stepuniti "be provided along each longitudinal side ofthe-'40 Rotation of the step treads relative to their endless series of step pockets to assume the lonrespective step pockets is controlled through treadgitudinalstresses of the-stairway; each suchwheels rotatably" secured to the step treads and chain havingrigid links and achain pitch equal throu'ghtread wheeltracks upon whichthe'tread to the step pitch of the stairway so that the step wheels roll, the tread wheel tracks being'suitably' axles pass through-hollow c'h'a'in pins of such 45. related to the path-taken by the step pockets to chains or serve as the chain pins thereof. Alter bring about such relative motion as is desired." nately; instead'of such running gear chains be-" The tread wheels and tread wheel tracks also serve ing structurally "separate from the longitudinal to support the free ends of the step'treads to sides'of-the' step pockets,- constructions may bel so maintain the step treads horizontal when the; employed in which portions or all of the same step units are in platform formation and when structure serve both as" links of running gear the step units change from platform formation-to chains which assume the longitudinal stresses stair formation, and vice versa. Preferably'eachofthe-stairway and. as'portions or; all of the lonstep tread is provided with only one tread wheel, gitudinal sidesof the step pockets. 7

at substantially midway between the sides of the Stairway sprocket wheels at each side of the stairway areiprovided at the lower landing for .way Espr'ocket transferring the step units from the return to the working run of the stairway, and vice versa. Similar stairway sprocket wheels at each side of the stairway are provided at the upper landing for transferring the step units from the working to the return n of the stairway, and vice versa, and for driving the stairway. These stairway sprocket wheels have a-chordal pitch equal to the step 'pitch of the stairway, and are arranged to engage either the step wheels on the step axles or other wheels or bushings concentric with the" step axles.

Stairway sprocket wheels having a relatively small number of teethare preferably employed in order that the size of suchsprocket wheels may not be inconveniently' large. In order to drive the stairway at a uniform linear speed by stairway sprocket wheels having such a relatively compensatingdrive is interposed between the upper landsmall number of teeth, a

ing stairway sprocketwheels and a uniformly driven drive sprocket wheel. drive causes the upper'landing stairwaysprocket wheels to rotate at cyclicallylvarying angular speeds in such manner that the inherent character ofsuch upper landing stairway sprocket cyclically diifering from a fixed value, when they are rotatedat a uniform angular speed, is compensated for. by suchlcyclic variations in the instantaneous angular velocit stairway :spr'ocket' wheels. l'he compensating drive herein illustratedscomprises; an auxiliary sprocket wheel mounted on thersame shaft-the drive shaft-upon which-the upper landing stair-- wheels .are mounted .and keyed,"

Y vthe auxiliary sprocket wheel, however, being freely rotatablewith respect to such shaft, and being positioned adjacent to, and at the outerside of, one of the-upper-landing stairwaysprocket'wheels. Theauxiliary sprocket wheelisdriv- Y en at a1miform=angular speed by means of a table drive chain connecting it andthe drive mt wheel.

ofttbe position ofthe disc about the'drive shaft. This din has formedrtherein anannular cam groove of uniform radial width the inner surface ofwhich is at an-irregular radial distance from the axisof thegdrlve shaft, the irregularity consistingof a series of variations in the radial distance of the inner surface of thefcam lroove from the axis of the drlve shaft; and there being as many points or lobes of maximum raq ,jdi'ai distance as, there are numberof teeth-in, A cam roller, ar

each stairway sprocket wheel.

ranged tent in the cam groove with but a small clearance, is rotatably mounted at one end of afllinke ff'he other end of this link is pivotally secured to the auxiliary} sprocket wheel through aseeond link. 'Iheflrstlinkis also, pivotallysecured'between its; ends to a pin mounted on the adjacent upper landing stairway sprocket wheel andextendingthrougha suitableslotted aperturein the auxiliary'sprockei; iwheel. With this construction; as the auxiliary sprocket wheel rotates, the linkage connected theretorotates and causes the cam rollerto roll on the outer orthc inner; surface: of thecam groove, depending upon whether. the auxiliary-sprocket, wheel is rotated This conpensating of. the upper landing.

Also. mounted upon the drive shaft is a disc, normally held stationary by. sultmeans which preferably aflords adjustment mmucam roove, t e 11- dial displacements of the cam roller end orthe first link cause angular displacements of the upper landing stairway sprocket wheels relative to the constant speed auxiliary sprocket wheel. with the result that the upper landing stairway sprocket wheels are driven at cyclically varying angular speeds. I

Other features and advantages will become apparent from thespeciiicatio'n taken'in conjunction with the accompanying drawings;

In the drawings: t

Figure 1 is a side elevation of the upper landing, portion of a moving stairway in accordance with the invention, with certain parts broken away and certain other'parts shown in section;

Figure 218 end view of the stairway at the upper landing looking in-the direction of the lower landing;

Figure 3 is aplan view of a portion of the stairway drive at the upper landing;

, Figure "4 is a sectional view of the stairway taken along the line 4-4 of Figure 2;

Figure 5 is a plan view of one step unit and related apparatus, taken as indicated by the line klofFlgm-es; W c

Figure 6 is-an enlarged view of aportion of a step unit taken along. theline Hi! Figure 4 wheels to impart to the'stairway linear speeds Figure '10 is a sectional view or a step unit,

taken along the line il-'-'-ll; of Figure Figure :ilais -,a schematic :viewjof, the lower landing portion of-a moving stairway in accordance with :the invention, illustrating diagrammatically thev manner inwhich thesteptreads of the step units are reversed in direction-, at the lower landing;

Figure 12 is a plan view of an alternate construction fora; step unit and related apparatus in accordancewith the invention, with certain parts broken away and certain other parts shown in sectionn- Figure -13 is a sideelevation of the step unit shown'in Figure 12, taken-.aiongthe line Ii-Hl of-Figurel2; r

Figure 14 is. an endview of the step .unit and takenalong the .lineiL-il;

related apparatus, of :Figure v13; v

Figure 15 is a sectional viewof a taken along the line iS-i I of Figure '14;

Figure 16 ls-a sectional view of a step unit taken along the line IFI)! Figure 14; Figure l7.is;a longitudinal sectional view of the stepunitof Figure 13v showing the position l of the parts whenthe, stepunit is on the inclined working run of stairway; a sectimalview similar to thatof- 'Figure,1'l, illustrating portion of the Figure l8 is the position :of the parts when the step unit is on the inclined portion of .thereturnrunofthestairwa; planview of another, alternate. a step unit andrelated appara-;

Figure 19 is .a construction for tus in accordancewith invention. with certain parts broken away and certain other parts shown in section;

vFigure-20flisia sideelevation, of the stepson, shown in Figure 19,

taken along the-lines 20-2.

of Figure lil;

Figure 21 is an end view of the step unit and related apparatus taken along the line Ii-Il ,of 1"lgure20;

portion of step Figure 22"is a sectional taken along the line 22-22 Figure 21; ,I

Figure 23 is a sectional view of aportion of a step unit, taken along the line ure 21;

, a 19, showing the parts when the portion ofthe working rnn of the Figure 24, illustrating theposition of 1 the parts step unit comprisesa step tread two longitudinal step pocket a transverse side 4| connecting longitudinal s ides 43 and 42, transverse side 4| 'servingas the riser for the step tread of the next adjacent step unit. Step axle 36 ends of the longitudinal sides 40 and 42 opposite the ends thereof connected, by transverse side 4|. Step tread 34 is pivotally mounted at .its nose 34a upon step a I relatively to the sides thereof,

transverse side 4| being concave in shape so that a constant clearancebetween it and the free end of step tread 34 is maintained as the step tread rotates in the step pocket .-,The pivotal mounting for step tread 34 is effected by step tread bearings 43 secured to the underside of step tread 34 (Figure 8),-bearings 43 engaging step axle,3.6.

Step ,axle 36 also serves; as

jacent step units. through apertures the ;step pocket 33 and also through apertures of straps 44 that are suitably. secured, at each side of the stairway, to the transverse side 4| of the step pocket of the next adjacent step unit (Fig- Thus, step axle 36 extends ures '1 and 10) .Thelower portions of straps 44.

for each step unit extend under the transverse side of the step pocket ofthe correspondingstep unit and into the path of the pivotal movement of the corresponding step tread 34 about'itsstep axle 36, to form stops 45 (Figure 10). Stops 45 serve to limit the movement of the step treads and to support thefreeends of when the respective step units are along the inclined portion ofthe upper, orworking, run of the stairway, as illustrated at the extreme left of Figure 1. j

Each step axle'36 extends beyond each of the longitudinal'sides of its corresponding step pocket and on each such extension of step axle 36 is rotatably mounted the step wheel 31 for the corresponding side of the stairway. In so mounting each step wheel 31,

at its outer end a collar .41 which serves to prevent outward {axial motion of the. step wheel,

view of a step unit '23-:23 of Fig'-' v H body 50 (see Figure Figure 24: is'alongitudinalsectionalviewof the the position of step unit, is on the inclined,

stairway; and Figure 25 is a sectional view similartto thatof' v v v y 5| on eitherside of" unit is'on' the inclined portion ,ofjj I a Q having a diameter 1-11 of they drawings, a'

Each I tread wheel'38,

sides 46 and." (Figure 5),,and

extends transversely between the,

axle 36. so that it may rotate .in

the hinge or pivot, pin for the hinge or pivotal connection of adin the longitudinal sides of 35 of the corresponding step unit a formed at the top the step treads positioned I v a bushing 46 (see Figure 6) is preferably interposed 'between such step wheel and'the step axle. Bushing 45, has formed collar 41 being secured to step axle 36 by means i of a suitable cotter or taper pin Each step wheel 31, inthe construction ll lustratedfinFigures l-ll, is formed of a metallic i 6) with a non-metallic tread surface 5|, disposed I circumferentially-compressed fabric squares, suitably fixed to, metallic body'53. A's illustrated, each step wheel 31 is preferably provided with two suchnon-metallicftread surfaces an" exposed cylindrical sursuchjas phenol canvasforfradiallyi face 52 of body member 50;,cy1iridrica1'surface 52 metallic tread surfaces 5| 'At'upper landing 32 two stairway sprocket wheels 53 are provided, one

at each side of the stairway securedtoa driveshaft54 (see Figure 2). Each stairway sprocket 'wheel 53 isarranged to engage cylindrical surfaces 52 of step wheels 31 at thecorresponding side Offth stairway, and in this fashion to drive'the stairway, aswill appear as the description proceeds. At lower landing 3| similar stairway a are provided, only one suchsprocket'wheel being shown in'Figure ll.

Where step wheels 31 are not engaged by any stairway sprocket wheel, they roll "upon, and are guided and supported by, suitable tracks 56 and 51, tracks 56 being the tracks on which the'step wheels roll while moving on the upper; or working, run of the stairway and tracks on which the step wheels "roll'while moving on the lower, or return,. run "of ,thestair- 56 and 51 extend way. Preferably tracks to and slightly beyond a point-vertically above, and a point vertically below, respectively, the axis 'ofdrive shaft 54, asillustrated-in Figure l, in order to insure the 4 v for each step unit by the tracks; at all-times except when cylindrical surfaces 52"of'the step wheels are thoroughly seated in the recesses formed in stairway sprocket wheels 53 A'similar construction is'lilr'ewise' employed at the lower landing. In addition to step wheels, up thrust provided.

tracks 56 and 51 for the '-In the construction illustrated in' Figures l-ll. I

step axle 36' of each step unit-is connected at it y to the step axle" of by means'of a'running 6| the chain pitch of which is equal e. the distance between two Chain '6 is provided with through which extend step" each side of the stair each adjacent step unit gearv chain to the step pitch (1. adjacent step axles). hollow chain pins' axles 36, chain 6| being positioned between step wheels 31 and the longitudinal sides of steppockets 35.

Tread wheel 38 for each step unit is rotatably mounted upon the corresponding step tread at the underside thereof. Preferably there is only sprocket wheels 55 continuance of a support tracks 53 and 59 are also less than that of the nona 30 tracks 51 being the.

"60. one, such tread wheel for each step tread, and preferably such tread wheel is-positioned substantially midway between 'the sides of the step tread. In the construction illustrated in Figures 1-1 1, tread wheel 33 is rotatablymounted upon brackets 62 and 63 (Figure 2) that are suitably secured to theunders'ide of the :step tread and a project downwardly therefrom along of tread wheel 38. Tracks'for .tread wheels 33 are provided at the lower and at the upperlandings, track 64 being the tread wheel track atthe lower landing (Figurell), and track 65 being the tread wheel track at the upper landingfFigures 1 and 14).

Considering the progress of one step unit,

either side wheel track 64 is engaged by the tread wheel of such stepunit on the return run of the stairway (assuming the stairway to be operating in theascending' direction) as thestep unit. approaches the lower landing. Tread wheel track 64 is shaped so that, as the step unit at the lower landing is', transferred from the return run to the upper, or' working, run of the stairway inward,

movement oflthe steptread with respect to the corresponding step pocket and the associatdportions 'of the running gear chains (as diagrammatically represented by, the dot-and dash line 66 in Figure 11) is controlled so as gradually to bring the step treadto the horizontal position as it passes underthe combplate 81 landing. At this time the free end of the step tread is supported by tread wheel track '4 through the intermediary of tread wheel 38. a

Tread wheel track 64 is shaped so as to support andmaintain the step tread horizontal while the corresponding step pocket and theassociated portions of the running gear chains traverse the lower horizontal portion and the lower bend of. the working run of the stairway, and enter the incline portion of the, working the incline portion, step tread 34 appears to rotate downwardly with respect to the sides of its step pocket. however, is anupward rotation of the sides of the step pocket relative to the step tread incident .to the forming of the stair formation of the stairway. When the step unit is on the incline portion of the working run of the stairway, the free end of the step. tread is supported by stops, and tread wheel track is dispensed with.

As the step unitQwhile on .theincline portion 7 of the working run of the stairway, approaches the upper bend, tread wheel 38 of such step unit engages upper landing tread wheel track 65 (Figure 1). Treadjwheel track 65is shaped so as to support andmaintain step tread-:3 horizontal f" while the corresponding step pocket 33 and the associated portions of the running gear chains traverse the upper bend and the upper horizontal portion of the working run of the stairway. As;

the step unit traverses the upper bend and enters the upper horizontal portion, step tread 84 appears to rotate upwardly with respect to the sidesof its step pocket. e actual movement involved, however, is a sides of the-step pocket relative to the step tread Y incident to the forming of the platform formation of the stairway. v

Tread wheel 38 continues in engagement with tread wheeltrack after the step tread passes under the combplate, 6. at the upper landing,

" track 65 extending around drive shaft II at the brackets connecting upper landingso as to be engaged by the tread wheel as theassociated step unit is transferred from the upper or working run of-the stairwayto the lower or return run, and. asthe associated.

step unit traverses the initial portion of the return run, as illustrated in Figure 4. To assist in supin addition to supporting the track to suitable stationporting track 65, e

ary members, there is mounted on the underside of track 65, where it is vertically above drive shaft 54, a roller Ill arranged to'bear 'upon drive shaft 54 and roll over the surface thereof when the drive shaft rotates." Y

While the step unit is on the return run' of the stairway, the free end of step tread 34 is supported by the transverse side ll of the assoat the. lower.

run'of the stairway. As the step unit traverses the lower bend and enters The actual movement involved,v

.mentary.

downward rotation of the ends of the stairway. R

ciated step pocket 33 ment of an extension" of bracket 62; with such transverse side (Flguresll and .4).

sion 1|, is in 'e lmment with transverse side ll,

ing inflthe ascending shape of tread wheel are transferred by the stairway sprocket wheels 53 st the upper landing. trom'the working run to tain step head I horizontal while theassoclated as "a result of the. engage- I treadv with respect to its associated step' pocket, (still assuming'the stairway to be operasdirection) is caused byJthe track 65 as the step units step pocket ii fduring thei'irst stages of its transfer from the v tated inwardly with respect to the'steptread-and until such time as such rotation' brings"extension H into 'engagementwithtramverse side I to pre-' this direction,

vent further relativerotation in and is such-as thereafter to maintain extension 1 I in engagement with transverse sidell. Such shape for tread wheel track 65 servesto move the steptread with respect to the step pocket so that the tread wheel clears" drive shaft 54,

wheels and over the upper bend of the sprocket I In addition, it brings about and return run. maintains the working to thereturn runfis romaximum; outward motion of the step tread relative to the step pocket before the step'unit, in passing around stairway sprocket wheel' 58, reaches a'position where the action of gravity alone would cause such maximum outward motion of the st'cp treadp" Asa result, the noiseand shock which would be incident to such outward motion as a result ofthe action of gravity,if-permitted,is avoided. v stairway is 7 operating in the -'de'-'. scending direction, the action of tread wheel' When the track-flat the upper landing is similar tothc action of tread cending operation of the stairway trea'd wheel tracks 84 Each step. tread 31 preferably comprises a step treadsupportfl, conveniently either a die cast-' ing or made of pressedsheet metal (see Figures 7--9) and a tread platen removably secured to the step tread support inanyconvenient'manner. Tread plate 13 is formed with cleats between which pass the teeth of the combplates at the It is to be observed that while a step unit is in motion on the incline portion of the upper; or working, run of the stairway,

the horizontal, or platform, formation to the stair formation, and vice versa, are made),,the only motion of a step tread'with respect to its immediate surroundings at either side is a gradual rotative one withrespect to the longitudinal sides of the associated step pocket, so that at these points also the risk of catching garments and the like is minimized.

The balustrading is indicated at 14 in Figure 2.

the longitudinal I wheel track at the lower-lamb ins. previously described in conjunction with asand if being functionally 'com'pleshaft 54,

(sometimes termed skirting board) of the balustrading at each side of the stairway adjacent the step treads is mounted a moulding strip, this moulding strip preferably extending for the entire working run of the stairway. For this moulding strip rubber may be employed, but it is preferred to employ an extruded metallic shape arranged to have a relatively small clearance betweenits lower end and the root of the cleat formations of the step treads. Moulding strip 15 thus not only serves to prevent foreign matter from falling into the region below the step treads, but to prevent outward rotation of the step tread with respect to the associated step pocket past the position which is normal when the step units are in platform formation.

Drive shaft 54 at the upper landing, in addition to having stairway sprocket wheels 53 mounted thereon and secured thereto (Figure 2), also has a handrail sprocket wheel 89 and the drum of a stairway brake diagrammatically represented by the rectangle 8|,'mounted thereon and secured thereto at one side of the stairway outside the plane of the. stairway sprocket wheel 53 at such side of the stairway. Handrail sprocket wheel 89 preferably drives the handrails through the intermediary of a suitable jack shaft parallel to drive'shaft 54 in order that the handrail. at each side of the stairway may be driven in unison with each other and with the stairway step units.

Drive shaft 54 is supported by means of bearings 82 positioned at either side of the stairway between stairway sprocket wheels 53 (Figure 2). Bearings 82 are shown as split bearings, but, if desired, may be roller bearings. Each bearing 82 is mounted on a plate 83 which is supported from a cross beam 84by means of a pair of cantilever brackets 85 (Figure 4) Stairway Along the portion width is thereby reduced.

The stairway is driven by a suitable motor 86 (Figure 1), through the intermediary of re-, duction gearing 81, sprocket wheel 88, drive chain 99, of compensating drive generally designated 92, and the left hand stairway sprocket wheel a 2, and further, for driving the other side of the stairway, through the intermediary of drive shaft 54 and the right hand stairway sprocket wheel 53, since both stairway sprocket wheels 53 are keyed to drive shaft 54. Compensating drive 92 is provided, when stairway sprocket wheels 53 having a relatively small number of teeth such as five (as is illustrated) are employed, in order to drive stairway sprocket wheels 53 at an angular speed which varies cyclically in such a manner variations in the linear speed imparted to the step units incident to the employment of stairway sprocket wheels 53 of such character.

' Compensating drive 92 comprises a. normally stationarydisc'93 mounted coaxially with drive disc 93 beingprevented from rotating of a link 94 one end of which is eccentrically connected to disc 93 and the other end of which is adjustably fastened to a fixed member 95. Disc 93 has formed therein anannular cam trough 95 in which operates a cam roller 91, cam trough 99 and cam roller 91 being of such size that cam roller 91 may roll freely on either the outer cam surface or the inner cam surface of annular cam trough 95 with only a small clearance between the cam roller and the other cam surface. Cam trough 98 differs from a circular trough of a given outer and inner by means as to reduce the tain other apparatus,

radius by the provision of a number of lobes 98, number of teeth in each sprocket wheel 53, in which, at each'lobe, the inner and outer radius of the cam trough are greater than such given radius. Cam roller 91 is rotatably mounted at one end' of a link I99, the other end of which is pivotally connected to one end of a second link IN. The other end of second link |9| is pivotally secured to sprocket wheel 9|, wheel being mounted coaxially with drive shaft 54 and so as to rotate relatively thereto. Left hand stairway sprocket wheel 53 is secured to link |99 by means of a pin I92, one

end of such pin being fixedly secured to the stairway sprocket wheel and the other end, after passing through a suitable recess I93 in sprocket wheel 9|, pivotally supports link I99. In operation, sprocket wheel 9| of compensating drive 92 is driven by motor 86 at a substantially constant speed. Rotation of sprocket wheel 9| causes rotation of linkage I99 and IN about'drive shaft 54, and thus causes movement of cam roller 91 in cam trough 96. Assuming the rotation of sprocket wheel 9| to be in the clockwise direction as viewed in Figure 1, cam roller 91 operates on the'outer cam surface of cam trough 96. Should cam trough 96 be a true circle, link |99 would not oscillate about pin |92 as sprocket wheel 9| rotates, and thus the stairway sprocket wheels 53 would be rotated synchronously with sprocket wheel 9|. Due, however, to the irregular shape of cam trough .95, link I99 oscillates about. pin I92 as sprocket wheel 9|, rotates, and as such oscillation of link |99 about pin |92 advances or retardsstairway sprocket wheels 53 with respect to sprocket wheel 9|, stairway sprocket wheels 53 are driven angular speed.

In the stairway construction illustrated in Figures l-ll, it is to be observed that separate running gear chains 6| areemployed at each side of the stairway, these chains taking most of the horizontal stresses of the stairway. If desired,

such separate running gear chains may be dispensed with, and portions of the step pockets made suiilciently strong to withstand the longitudinal stresses of the stairway. This is conveniently effected by composite structure which serves both as the longitudinal sides of the step pockets and as links of a running gear chain connecting adjacent step axles.

Illustrative of such a const ction is the construction shown in Figures 12-18, wherein the stairway Comprises a plurality of step units generally designated ||9 pivotally mounted together to form an endless series of step units. Each step unit ||9 comprises a step tread I, a step pocket generally designated H2, a step axle 3, two step wheels H (one at each side of the stairway) ,and a tread wheel H5, together with ceras will become apparent as the description proceeds.

Step pocket ||2 has two longitudinal sides, each of which is formed of two overlapping links H9 and H1 suitably secured together, preferably by bolts, as illustrated. Step pocket 2 alao has a transverse side connectingthe twolongitiidinal sides, thetransverse sideibeing formed of two curved plates ||8, each secured at one end,.as by welding, to the link l1 at the corresponding the other end of "P '!9 being in abutting relation and being-secured together, preferablynby. bolts, as illustrated. Plates ||8, as the transverse side of step pocket H2, serve as the riser for the step tread of the leading end (assuming the stairway to be in opmeans of a'projection I23 I30 in links II6.

eration in the ascending direction), a bushing I20 (Figure 12), through which extends step axle I I 3 for the preceding step unit. Each link I I5 of a step unit is formed witha circular aperture I2I to fit over bushing I20 on the link 1 of the succeeding step unit. Links H6 and H1 for one step unit thus not only serve as the longitudinal sides of the step pocket for such step unit and pivotally connect such step pocket to the corre- SDOIldiIlg longitudinal sides of the step pockets of the adjacent step units, butalso as a link of.

a single link running gear chain at the corresponding side of the stairway capable of withstanding the longitudinal stresses of the stairway.

In installing the stairway, links II6 and H1 at each side of the stairway need not be uncoupled for any step unit except for the final step unit which connects the ends of the step units to make an endless series thereof. After initial installation, repairs may readily be made to any part of any step unit without dismantling the entire stairway, by uncoupling links H6 and H1 for such step unit and link II6 for the preceding step unit, and also by unbolting the two plates III! that serve as the transverse side for such step unit.

Each step axle I I3 extends outwardly beyond the bushing I20 at each side of the stairway through which it passes, and on each such extension of step axle I I3 is mounted the step wheel II4 for the corresponding side of the stairway. Step wheel H4 is similar to step wheel 31 illustrated in Figures 1-11, and is mounted on the step axle in asimilar manner, bushing I22 being the bushing for step wheel II4 corresponding to bushing 46 for step wheel 31. To prevent rotation of step axle II3 with respect to link bushing I 20, link bushingl20 and bushing I22 are interlocked at one or both sides of the stairway by on the former fitting within a suitable recess provided in the latter.

Tread wheel H5 for step tread III is rotatably mounted thereon at the'underside thereof,'and

operates similarly as tread wheel 38 of Figures 1-11. Stops I24 andextension I25 support the free end'of step tread III and determine its inward and outward limits of motion, respectively, similarly as stops 45 and extension II of Figures 1-11.

Each step axle II3 is'concealed from view for the entire width of the stairway by extending the upper portion of the adjacent plates I I8 up under the edge of a downwardly projecting lip I26 of the step tread support I21 for tread plate I20, this lip being arranged to overlap the upper portion of plates H8 at all times, and with a substantially constant clearance so that there is no pinching hazard. Lubricant for link bushings I20 may be introduced in any desired manner through apertures The possibility of leakage of such lubricant intothe region between the pairs link, assuming the associated of links H6 and H1 at each side of the stairway is remote, but as a final guard for preventing lubricant from working its way out to the visible portions of the stairway, the portions of plates H8 at each side of the stairway are further ex-.

tended, as at I3I so as more completely velop the step axle (Figure 16) Another construction in which the same structure serves both as the longitudinal sides of the step pocketsand as links of a running gear chain connecting adjacent step axles, is illustrated in Figures 19-25. The step unit I40 thereof comprises a step tread I, a step pocket generally designated I42, a step axle I43, two step wheels I44 (one at each side of the stairway), and a tread wheel I45, together with certain other apparatus, as will become apparent as the description proceeds.

Each of the two longitudinal sides of step pocket I42 comprises a link I46 and a longitudinal side I41 of a shield I48. Link I46, together with a link I50 parallel thereto but spaced therefrom, serve as links of a double-link running gear chain at the corresponding side of the stairway capable of withstanding the longitudinal stresses of the stairway,.links I46 and I41 for'alternate step to enunits being secured'together by hollow chain pins I5I, and links I46 and I41 for the'other step units being secured together by chain sleeves I52 which are fitted about, and rotatable with respect to, hollow chain pins I5I. Each link I46, and thus each step pocket I42, is thereby pivotally connected to each adjacent step pocket. Each link I46 is formed with a triangular-shaped extension I53 at the underside of the leading end of such step unit to be on the working run of the stairway and moving in the ascending direction.

Shield I48, conveniently of pressed metal, comprises the previously mentionedtwo longitudinal sides I41, one adjacente'ach link I46 at either side of the stairway, and also comprises a transverse side I54 connecting the two longitudinal sides I41. The lower edge of each longitudinal side I41 of shield I48 is flanged, and by means of bolts passing through these flanges and through suitable projections I55 from the following edges of triangular-shaped extensions I53 of link I46, shield I48 is removably secured to'links I46 at either side of the stairway. Whenshield I40 is in place, transverse side I54 thereof serves as the transverse side of step pocket I and thus, as the riser for the step tread of the next adjacent step unit. a

Step axle I43 extends through and beyond corresponding hollow chain pins I5I ateach side of the stairway, axle I43 is rotatably mounted the step whe'el I44 for the corresponding side of the stairway. In so mounting each step wheel I44, a'bushing I56 is preferably interposed between such step wheel and the step axle. Bushing I56 hasformed at its outer end a collar I51 which serves to prevent outward axial motion of the step wheel, collar I51 being secured to step axle I43 by means of a suitand on each such extension of step of transverse side I54 being such that there is a uniform clearance between such side and the free operates similarlyas tread wheel 38 of Figures 1-11. Stops I63 and extension I64 support the free end of step tread I'4I and determine its inward and outward limits of motion, respectively, similarly as stops 45 and extension ures 1-11..

Each step axle I43 is, concealed from'view for the entire width of the stairway by extending the upper portion of transverse side the edgeof a downwardly projecting lip I65 of the step. tread support I66 for tread plate" I61, this lip being arranged to overlap the upper portion of transverseside I54 at all times, and w h a substantially constant clearance so that there is no pinching hazard.

- With the construction illustrated in Figures 19-25 it is preferred'to provide a chain roller I68 about each chain bushing I52 and to have the stairway sprocket wheels engage such chain rollers, instead of engaging the tread wheels; The chordal pitch of the stairway sprocket wheels, however, remains equalto the step pitch of the stairway.

In fabricating a stairway in accordance with the construction illustrated in Figures 19-25, two double-link roller chains may be fabricated in accordance with standard practice, but employing step treads I4I may traversing the working run for one of the two series of links for such chain the special shaped links I46. ,Shields I48 and step tread supports I66 may readily be formed from appropriate sheet metal stock. In installation, the double-link chains formed of links I46 and I50 at each side of the stairway, together with step axles I43, sleeves I62, bushings I56 and step wheels I44, may be installed at the same time. Thereafter, shields I48 may be inserted between corresponding links I46 at opposite sides of the stairway and secured in place, and then be mounted upon the step axles. After initial installation, repairs to, and replacements of, any part of a step unit may be made readily and with a minimum dismantling of other parts of such step unit, and of other step units. 1

Inasmuch as many changes could be made in the above constructions and as many embodiments of this invention other than the three herein described and illustrated could be made without departing from the scope thereof, it is in tended that all matter contained in the above de scription or shown inthe accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a moving stairway; an endless series of movable step units each having a step tread pivoted at its nose to the corresponding step unit; and means for maintaining the step tread of each step unit horizontal while such step unit is of the stairway.

2. In a moving stairway; an endless series of movable step units each having a step tread pivoted at its nose to the corresponding step unit; and means on each step unit supporting thereby the free end of the step tread of such step unit and causing such step tread to be horizontal while MI is rotatably II of'Figsuch step unit is traversing the incline portion of the working run of the stairway.

3. In a moving stairway; an movable step units each having a step tread pivoted at its nose tothe corresponding step unit; means, including a tread wheel rotatably mounted upon the step tread of each step unit at the underside of such step tread substantially mid-. way between its sides, and also including a tread wheel track, in the vicinity of the lower and the upper landings, upon which the tread wheels for said step units roll, for supporting the free end of the step tread for the corresponding step unitand ca using such step tread to be horizontal while such step unit is traversing the lower and upper horizontal portions, and the lower and upper bends of the working run of the stairway; and means on'each step unit supporting thereby the free end of the step tread of such step unit and causing such step tread to be horizontal while such step unit is traversing the incline portion of the working run. of the stairway.

4.. In a moving stairway; an endless series of step units each having a step axle extending transversely across the stairway and a step wheel mounted thereon at each side of the stairway rolling on astairway track; a step tread for each step unit pivotally supported at its nose on the step axle for the correspondingstep unit; and means for maintaining the step tread of each step unit horizontal while such step unit is traversing the working run of the stairway.

5. In a moving stairway; a plurality of movable step units each comprising a step pocket and a step tread; means connecting the step pockets of adjacent step units so as to form an endless series thereof; means supporting each step pocket comprising a step wheel rotatably mounted upon each step pocket at each side of the stairway and two step wheel tracks, one at each side of the stairway, upon which the step wheels at the corresponding side of the stairway roll; means pivotally mounting each step tread at its nose upon the step pocket of the corresponding step unit so that such step tread may rotate with respect to the sides of such step pocket to an inwardly r0- tated position in which such step tread is surrounded at its three sides away from its nose by the sides of such step pocket; and means controlling the position of each step tread with respect to its corresponding step pocket for maintaining the step tread of each step unit horizontal while such step unit is on the working run of the stairway, the step tread of each step unit rotating relatively to the sides of the step pocket of such step unit as such step unit traverses the lower and upper bends of the working run of the stairway and the step tread of each step unit being in said inwardly rotated position while suchstep unit is on the incline portion of the working run of the stairway.

6. In a moving stairway; a plurality of independent step units each comprising a step pocket having two longitudinal sides and a transverse side and each also comprising a step tread supendless series of ported upon the corresponding step pocket so that sides and a curved transverse side connecting said two longitudinal sides near one end thereof, the center of curvature of said transverse side being along a transverse axis near the other end upon said step axle; and means for limitingthev inward and outward motion of said step tread in said pocket.

8. In a moving stairway; a plurality of ,in-

' dependent step units each comprising a step pocket having two longitudinal sides and a transverse side and each also comprising a step tread supported upon the corresponding step pocket so that the three sides thereof extend above the plane of the step tread of such step unit; and means pivotally connecting adjacent step units to form an endless movable series thereof, the longitudinal sides of said step pockets acting as chain links to drive the step units.

9. In a moving stairway; a plurality of step units with pivoted rigid links connecting, adjacent step units so that said links serve as an endless chain having a chain pitch equal tothe step pitch of the stairway; rollers coaxial with the pivots of said links; a stairway sprocket wheel engaging said rollers for drivingsaid stairway, said stairway sprocket wheel having a chordal pitch equal to the step pitch of the stairway, and having a relatively small number of teeth; and means for driving said stairway sprocket wheel at a cyclically varying angular speed from a uniformly driven cause said stairdrive sprocket wheel in order to way sprocket wheel to drive said stairway at a uniform linear speed, said means comprising; an auxiliary sprocket wheel rotatably mounted adjacent to and coaxially with said stairway sprocket wheel and also rotatable with respect to said stairway sprocket wheel; means coupling said auxiliary sprocket wheel with the uniformly driven drive sprocket wheel so that said auxiliary sprocket wheel is driven at a substantially constant angular speed; a disc stationarily mounted adjacent and parallel to said auxiliary sprocket wheel, said'disc having formed therein an annular cam groove of uniform radial width the inner surface of which is at an irregular radial distance from the axis of said auxiliary sprocket wheel, the irregularities consisting of a'series of gradual variations in the radial distance of the inner surface of the cam groove from saidaxis to form a series of lobes equal in' number to the number of teeth in said stairway sprocket wheel; linkage connecting said auxiliary sprocket'wheel with said stairway sprocket wheel; and a follower, operating in said cam groove, mounted on said linkage and serving as the fulcrum thereof.

' WILLIAM SEBASTIAN RAPE-BAKER. 

